A semiconductor manufacturing apparatus such as a diffusion apparatus, an etching apparatus or a sputtering apparatus includes a gas supply system that supplies a gas originating from a processing gas supply source, e.g., a gas canister, to the semiconductor manufacturing apparatus. At the semiconductor manufacturing apparatus, a processing target substrate such as a semiconductor wafer undergoes a surface treatment or the like as a semiconductor device manufacturing process, e.g., a film formation process or an etching process, is executed by using the specific type of gas supplied via the gas supply system.
Depending upon the type of processing executed during the semiconductor wafer manufacturing process, a highly corrosive gas such as chlorine gas or silane gas may be used and accordingly, various attempts are made toward clean gas supply by, for instance, constituting the gas supply flow passage with a gas piping material, e.g., SUS 316L, with better corrosion resistance than the materials typically used in the related art. For instance, there are gas flow passages partially or entirely constituted with a specific type of austenite stainless steel to assure good corrosion resistance over welded areas of the gas piping through which chlorine gas or silane gas is distributed (see, for instance, Japanese Laid Open Patent Publication No. H05-068865).
However, even when a gas piping constituted of stainless steel is used as a gas supply flow passage as described above, corrosion of the gas piping cannot be completely prevented, depending upon the type of corrosive gas supplied through it. In other words, the corrosive gas may react with the metal constituting the gas piping to form an undesirable metal compound or corrode the gas piping to result in contamination of the corrosive gas by the metal component (Fe, Cr or Ni) constituting the gas piping. A fluorine-containing corrosive gas (e.g., HF gas, F2 gas or ClF3 gas) in particular is extremely corrosive and even a gas piping constituted of stainless steel cannot be completely protected from corrosion caused by such a fluorine gas. Rather, the metal component contaminates the fluorine corrosive gas and also, the fluorine gas reacts with the metal constituting the gas piping and through the reaction, an undesirable metal compound (metal fluoride) is created.
The metal compound, the metal component and the like occurring in the gas supply flow passage as described above may be captured at a gas filter disposed in the gas supply flow passage so as to prevent their entry into the semiconductor manufacturing apparatus. Japanese Laid Open Patent Publication No. H05-068826 discloses a structure that includes a gas filter disposed in the gas supply passage of a heat treatment apparatus, so as to capture particles at the gas filter.
However, it has been learned that the metal compound or component present in the gas supply flow passage may not always be solid metallic particulates (e.g., particles) that can be captured at a gas filter and instead, and that they may assume a volatile metal component state (e.g., a vaporized state), in which case, they cannot be captured at the gas filter. This means that the metal compound and the metal component occurring in the gas supply flow passage cannot be thoroughly removed simply by disposing a gas filter in the gas supply flow passage.
A volatile metal component that passes through the gas filter subsequently enters the semiconductor manufacturing apparatus together with the corrosive gas. Once it enters the semiconductor manufacturing apparatus, it causes metal contamination, e.g., formation of particles over semiconductor wafers.
As ever higher integration is achieved in semiconductor devices to assure higher performance in recent years, even the metal contamination attributable to the volatile metal component can greatly affect the product yield, quality and reliability. Device defects attributable to metal contamination include defective patterns and degraded electrical characteristics.